Issue 48

A. Metehri et alii, Frattura ed Integrità Strutturale, 48 (2018) 152-160; DOI: 10.3221/IGF-ESIS.48.18

In the particle In this case the presence of a crack (parallel to the interface particle/matrix) in particle is considered and the effect of the different ratio of reinforcement and loading conditions on the energy of crack propagation characterized by the stress intensity factors are taken into account. The crack length is equal to 50µm and the distance between interface and crack in particle is c=5µm. Fig. 6 shows the normal and shear stresses distribution at the crack tip given for σ=200MPa. Fig. 7 shows the variations of K I and K II stress intensity factors with the different aspect ratio of reinforcement and applied load under mode I loading. It can be seen that for all applied loads, in general, for the crack length (a=50µm), K I and absolute K II values increase. Furthermore, one can notice that the opening and the sliding mode of the crack are more intense in the cases of existence of the crack in the particle. It can be also noticed that the existence of a crack in particle facilitates the sliding of the crack. At the same time it facilitates the opening of the crack propagation because the values of K I and K II in particle are higher than the values of K I and K II in matrix which is due to the high elastic modulus of the particle. The increase in K I value is linear depending on the ratio of reinforcement. It is observed that the maximum value of K I or the maximum absolute value of K II are registered at y/z=1 (K I 20 MPa.mm 1/2 for a=50  m) under mode I loading. The level of this stress intensity factors decreases with the increase in the y/z ratio.

(b)

(a)

Figure 7 : Variation of K I

and K II

with ratio of reinforcement and applied load for the crack in the particle.

Inter-distance effect on the SIF In this part, we study the inter-distance effect of the two interfacial cracks between two cubic particles on the evolution of the stress intensity factors K I and K II is considered. The distance ‘d’ is the interdistance separating the interfacial cracks tips from the first particle and the second particle as presented in Fig. 2c. The displacement of the interfacial cracks of length a=50µm are parallel to the y-axis. The results obtained for the applied loading conditions for σ=150MPa are illustrated in Fig. 8.

Figure 8 : Mechanical stress distribution at the crack tip cases of interfacial crack–crack interaction (two cubic particles interaction for σ = 150MPa).

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